If you follow the guidelines of L'Eroica & Cl Rendezvous (as good as any out there) it should be 1987 or earlier, lugged or filet brazed steel with friction shifters (DT, bar-end or stem mounted). Much older bikes have shifters in other places. No clipless pedals. No lycra. I think freewheel should be 6 or fewer cogs, but what do I know.

L'Eroica deviated for certain special bikes, , as Bianchi built a bike honoring the spirit of the event and old-time cycling.

In the interest of congeniality & civility = anything you want C&V to be. Detailed pics required so everyone else can debate the merits of your nomenclature.

Extra cred for tubulars, wooden wheels, European & UK frames, kerosene lamps, etc.